It's certainly a good possibility to be a seed. Not sure of the size of those. And it's hard to tell how close to the camera it was. Kinda looks big! So if not a paper bag or flying inflatable raft, then it must be a Elm seed. Good researching :)

The object and leafs on the right move in tandem, the breeze blows both in the same direction.

The focus of the camera seems to be on the objects closest to the lens, the leafs on the right and the pole, as the object comes into shot it seems to be focused at the top of the picture, fuzzing as it moves away. I would say that the object, leafs and pole are all in the same area.

When the object is surrounded by sky, it looks bigger, by placing the object next to the leafs we see comparison